The Enlightenment Foundation Libraries (EFL) cover a wide range of functions including inter-process communication (IPC), graphics, audio and even location services. Other powerful features include file handling utilities, widgets and user interface controls, thumbnailing and rendering via scene graph. You can discover more of EFL's capabilities by visiting the About EFL page.
The Unified EFL API (Currently in BETA) is a reworking of the old many-libraries API into a single (Efl) namespace. It is build on top of Eo (Enlightenment Object) class definitions to provide inheritance of objects and to bind more closely to higher level languages.
The Efl API is split into three main areas:
Efl_Ui, each encompassing the one before so you can include a single reference in your app. For basic offline applications use Efl_Core, for additional network and connectivity use Efl_Net and if you are building a graphical application then use Efl_Ui. In the C language (the default for this documentation) you will also see reference to Eina which provides common data constructs missing in low level languages.